Sadly, the summer holidays are ending and the temperature's dropping but thankfully so are oil & gas prices - you can now get the cheapest energy deal since 2012, so it's ready & in place before winter's high use period.

This is our 3rd MSE energy collective switch - that's the official system where a trusted intermediary (eg, a council or us) runs an auction for energy firms to bid to provide special tariffs. Our huge 10m email recipients & 1.7m Cheap Energy Club members mean our winners smash the open market's best buys.

How to grab one of these tariffs: Collective switch rules mean you need to go via our Cheap Energy Club and fill in your details (not for NI, sadly). It's better if you've got bills to hand - if not, it can estimate - then it'll...

- Show your exact price, saving & compare it to ALL market tariffs. While our collective tariffs usually win, there can be regional & usage variations.

- Give £30 dual fuel cashback (£15 elec-only). Any time we can switch you (collective switch or not) we give this - sent roughly 60-90 days later.

- Monitor that it stays cheap. You set a 'trigger saving', eg, £75/yr, then we alert you if you can save this by switching again - perfect for fixed deals where cheap rates only last a short time. This takes the hassle out of energy tarting, where you constantly switch to get the cheapest rate.

MSE Big Switch III winner 1: The cheapest tariff (dual fuel & elec-only).This MSE E.on 12 month tariff will save someone with typical bills on a big 6 standard tariff £280/year and as it's a fix, the rate is locked in for a year. It's available for those wanting dual fuel, elec-only or Eco 7.

- Plus get £30 cashback from the Cheap Energy Club.
- Plus get up to 1,500 Tesco Clubcard or £15 high st voucher (eg, Argos) as you get 1,500 E.on reward pts over the year convertable into either. Though you must tick 'sign up to E.on points' during sign-up.

- Good for you if: 1) You want the cheapest. 2) You're OK switching in a year.

- Not for you if: 1) You want to be able to switch penalty free - though it's so much cheaper you could take this & pay the fee if you need to move. 2) You're moving home imminently (as you'd need pay exit fees).

- How's the customer service? Decent, 54% great and just 10% poor in our last poll. Plus, it was our Big Switch I winner and it handled the huge demand well (whereas Sainsbury's Energy in Big Switch II struggled).

PS: If you're on last year's 12 month E.on collective switch, you can switch now to this, no penalties, no problem.

MSE Big Switch Event III winner 2: The cheapest THREE-WINTER fix. For long term surety, the winner's MSE Green Star 36mth fix. It's available for dual fuel, elec-only or Eco 7. Many can slash their costs by nearly £200/yr and ensure no price hikes for 3 years. Plus you get our £30 cashback.

- Good for you if: 1) You don't usually switch and often forget - as do this now & you needn't act again until 2018. 2) You're worried about future price hikes and prefer to bag the certainty of a long-term cheap price.

- Not for you if: 1) You just want the cheapest price. 2) You want to be able to switch penalty-free. 3) You may soon move home (as you can't take it with you). 4) You want 100% renewable energy. This specific tariff, while reasonably green, isn't.

- How's the customer service? Green Star has only been around since 2013, so while it scored 77% great and just 2% poor in our last poll, that was on just 67 votes. It has won our collectives before & we've had few problems.

MSE Big Switch Event III: The cheapest GREEN tariff. The winning bid from a tariff that's generated 100% of its elec from renewable sources is this MSE Green Star 12mth fix - which fully complies with Ofgem's green tariff requirements without a huge premium to the non-green winner. It's for dual fuel, elec-only or Eco 7. Plus you get our £30 cashback.

- Good for you if: 1) You believe in green. 2) You want a competitive price, but will pay a little more for eco. 3) You're happy to switch again in a year.

- Not for you if: 1) You just want the cheapest. 2) You want to be able to switch penalty-free. 3) You'll move home soon (you can't take it with you).

- How's customer service? Green Star has only been around since 2013, so while it scored 77% great and 2% poor in our last poll, that was on just 67 votes. It has won our collectives before & we've had few reported problems.

MSE Big Switch Event III: The cheapest prepaid tariff.We tried for a key or card tariff, but no supplier's bid beat the market's best buys. Instead, just use our Prepayment Comparison to find your cheapest. However, even on them you'll still be paying £300/yr more than the cheapest direct debit deal. To see if you can switch to a standard meter, read Prepaid Gas & Electricity.

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The MSE Big Switch Event III FAQ

Q. What do I need to switch? A bill, preferably your annual bill, would be good - and use kWh rather than cost if you can. Yet if you don't have that, estimate your usage (if you're moving home the comparison does it for you) and while the answer won't be perfect, it shouldn't be too far out.

Q. Does MSE make money from this? Yes. Suppliers pay about £60 per dual fuel switch (£30/single fuel) to comparisons & collective schemes. We give £30 back to you as cashback (£15/single fuel), to encourage switching.

Much of the rest pays our suppliers: MoneySupermarket.com (part of the same parent group as MSE), which provides the underlying data & switch process; and Allfiled, the technology database platform. We expect to be left with about £11 per dual fuel switch - less than you get in cashback.

That'll pay the team who work on this, and hopefully leave some profit too. As always, we only ever write based on editorial independence in the consumer interest, as enforced by our legally binding editorial code.

Q. I'm already locked into a fix - should I switch? Our comparison allows you to see how much you'd save compared to your current fix & the price it'll go to afterwards. If you can save, check if that beats any exit penalties. PS: Firms CAN'T charge exit fees if you're within 49 days of the tariff ending.

Q. If prices are dropping, should I wait? British Gas may've just cut its standard tariff by 5%, but it's still on avg £280/yr more than our E.on fix. Other cheap fixes could of course launch, but factoring in the Tesco points this is on avg £40 cheaper than the next best (£70 with cashback), so that's a big gap.

Over the next year energy prices should come down further - though they'd need to be huge to substantially beat this, and switching now means saving immediately. If the world market did drop in an unprecedented way, the worse case scenario is you could pay the £30/fuel exit fee and switch, and it's likely in the meantime you'd have saved more than that anyway. See price predictions.

Q. I'm already with one of these providers (eg, E.on). Can I still switch? Yes (including our Big Switch I E.on winner), plus E.on & Green Star say they won't charge exit fees on their existing tariffs if you change to their winner.

Q. You're normally against exit penalties - why do these have them? Sadly all our cheap bidders had them. Yet our winners are so much cheaper, even if you decide to leave and pay the fee, it's often covered by savings.

Q. Can I switch if I've got a solar panels FIT tariff? Yes. Your FIT payer and your energy supplier are separate. When you switch energy firm, the firm that pays you for generating electricity doesn't automatically switch too, though you could switch it for ease if it supports it (Green Star doesn't).

Q. Can I switch if I've a smart meter? Yes, though you may lose some smart meter functionality by switching.

The 17 day big energy switch event III
Q. Who's responsible for these tariffs, MSE or the energy firm? The energy firm is responsible for supplying you, and you pay it. Yet we take our bit seriously and ask all providers to set up special customer help teams with max 48 hour response times. If something goes wrong, and it won't help, let us know and we'll try to help.

Q. If I'm on the Warm Home Discount, can I switch? Yes to Eon, no to Green Star which doesn't support it. Yet how this works depends on which type of discount you have, see Warm Home help.

Q. Is there a credit check? E.on does a full credit check (Green Star doesn't). In a few (1 in 50) cases it may ask for a £200/fuel security deposit. If so you can choose to stop the switch.

Q. Can I get paper bills? Yes, but the prices listed are for paperless. E.on charges an extra £5/fuel/yr and Green Star £7.50/fuel/yr for them.

Q. I'm supplied by an Independent Gas Transporter (IGT) - can I switch? Yes, both E.on & Green Star support IGTs at no extra cost.

Q. Where can I see the standing charge & kWh collective switch costs? They vary by region, so we display your exact cost in the Cheap Energy Club comparison result - just click the 'Feedback & Full Info' link.

Q. My direct debit is in credit - will I get it back if I switch? Yes and it could be by £100s. Ensure you ask the firm you're leaving for it (if not, some mightn't cough up). See Reclaim Energy Credit.

Q. I'm in debt with my supplier. Can I switch? Yes, usually, but it varies with supplier - some make you pay it off or get it under a certain balance. For prepaid tariffs you can always switch unless your debt's £500+.

Q. Is paying by monthly direct debit cheapest? Yes, typically £70-£90/yr less than other methods - just do regular meter readings so it's accurate.

Q. I got a cheap fix then it put my cost up? It's the rate that's fixed, ie, the price per unit, but what you pay depends on usage. If a firm's underestimated your usage (or you start using more) your direct debit can be increased even on a fix. If you think it's too high, you can ask for it to be lowered.

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